1. Technical Field
The present disclosure relates to an illumination device, and particularly to a light emitting diode (LED) lamp providing an adjustable color temperature.
2. Description of Related Art
At present, light emitting diodes (LEDs) are widely used due to high brightness, wide color gamut and rapid response speed. With the rapid development of decorative illuminations for both commercial and residential purposes, the demand for using LEDs in lamps for decorative illuminations is ever increasing.
It is important for the decorative illuminations to have a sufficient light energy in a correct color temperature since the color temperature affects the sensation of user's eyes. Thus, there is a need for a lamp which can emit light with an adjustable color temperature. However, the function of most conventional LED lamps for adjusting the color temperature is achieved by varying pulse width modulation (PWM) signals supplied thereto. Therefore, drive circuit for the LED lamps must include a PWM drive chip and many complicated peripheral circuits, which disadvantageously affects an illumination efficiency of the LED lamps and increases costs.
It is thus desirable to provide an LED lamp which can overcome the described limitations.